<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://code.jquery.com/jquery-1.12.4.js"></script>

</head>
<body>
    <!-- 设置表格序号为偶数行的文本颜色 -->
    <table id="tab">
        <tbody>
            <tr>
                <td>第一行</td><td>第一行</td>
            </tr>
            <tr>
                <td>第二行</td><td>第二行</td>
            </tr>
            <tr>
                <td>第三行</td><td>第三行</td>
            </tr>
            <tr>
                <td>第四行</td><td>第四行</td>
            </tr>
            <tr>
                <td>第五行</td><td>第五行</td>
            </tr>
        </tbody>
    </table>

    <script>
        // for (let i = 0; i < $('tr').length; i++) {
        //     i%2 != 0 ? $('tr')[i].style.color = 'green' : '';
        // }
        $('tr:odd').css('background-color','green')
    </script>
</body>
</html>